minBy

Returns the minimum value of an array, after mapping each element to a value using the provided function.

• Use Array.prototype.map() to map each element to the value returned by fn.
• Use Math.min() to get the minimum value.

const minBy = (arr, fn) =>
  Math.min(...arr.map(typeof fn === 'function' ? fn : val => val[fn]));

minBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], x => x.n); // 2
minBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], 'n'); // 2